At my kids' school, when each one was a kindergartener they made a plate as a Mother's Day gift. Since it was a surprise, I don't know exactly where they were ordered or how they're done, but I do know the kids drew a picture on a piece of paper and somehow it was sent to the company to be transferred to a melamine (plastic) plate. I've been using them for years - food safe, dishwasher safe, lightweight. It would be a really cool thing to maybe order a few of these "kits" or whatever they were and make multiple plates (depending on how many signatures you get).
ETA:
http://www.makit.com/ProductDetail.aspx?ProductCode=K1100&PK=8253e113-969a-4285-bba6-7528e8f6fab4 I don't know if this is exactly what my kids have given me, but it looks pretty much like it, I think!